Wireless position sensor

Claim 2

Apparatus according to claim 1, wherein the electrical current in the at least one sensor coil has frequency components at the different frequencies of the one or more field generators, and wherein the signal generated by the control circuit is indicative of the frequency components of the current.

Claim 3

Apparatus according to claim 1, wherein the one or more field generators are adapted to generate the electromagnetic fields at respective field frequencies, and the RF driver is adapted to radiate the RF driving field at a driving frequency, and wherein the one or more field generators and the RF driver are coupled to operate so that the field frequencies and driving frequency are mutually synchronized.

Claim 4

Apparatus according to claim 1, wherein the control circuit is adapted to generate the output signal so as to indicate a phase of the current flowing in the at least one sensor coil, relative to a phase of the electromagnetic fields.

Claim 5

Apparatus according to claim 1, wherein the control circuit comprises a voltage-to-frequency (V/F) converter, which is coupled to generate the output signal with an output frequency that varies responsive to the electrical current flowing in the at least one sensor coil.

Claim 6

Apparatus according to claim 1, wherein the transponder is adapted to be inserted, together with the object, into a body of a subject, while the one or more field generators and the RF driver are placed outside the body.

Claim 7

Apparatus according to claim 6, wherein the object comprises an elongate probe, for insertion into the body, and wherein the transponder is fixed in the probe so as to enable the receiver to determine the coordinates of a distal end of the probe.

Claim 8

Apparatus according to claim 6, wherein the object comprises an implant, and wherein the transponder is fixed in the implant so as to enable the receiver to determine the coordinates of the implant within the body.

Claim 9

Apparatus according to claim 8, wherein the implant comprise a hip joint implant, comprising a femur head and an acetabulum, and wherein the transponder comprises a plurality of transponders fixed respectively to the femur head and the acetabulum, and wherein the signal receiver is adapted to determine a distance between the femur head and the acetabulum responsive to the output signal from the transponders.

Claim 10

Apparatus according to claim 1, wherein the control circuit is adapted to operate powered solely by the electrical energy conveyed thereto by the power coil.

Claim 11

Apparatus for tracking an object, comprising: a radio frequency (RF) driver, adapted to radiate a RF driving field toward the object at a driving frequency; one or more field generators, adapted to generate electromagnetic fields in a vicinity of the object at respective field frequencies, in synchronization with the driving frequency; a wireless transponder, fixed to the object, the transponder comprising: at least one sensor coil, coupled so that an electrical current flows in the at least one sensor coil responsive to the electromagnetic fields; a control circuit, coupled to the at least one sensor coil so as to generate an output signal indicative of the current; and a power coil, coupled to receive the RF driving field and to convey electrical energy from the driving field to the control circuit, and further coupled to transmit the output signal generated by the control circuit; and a signal receiver, adapted to receive the output signal transmitted by the power coil and, responsive thereto, to determine coordinates of the object.

Claim 12

Apparatus according to claim 11, wherein the control circuit is coupled to receive a frequency synchronization signal from the power coil, responsive to the RF driving field, and to apply the frequency synchronization signal in generating the output signal.

Claim 13

Apparatus according to claim 11, wherein the driving frequency of the RF driving field is an integer multiple of the field frequencies of the electromagnetic fields of the one or more field generators.

Claim 14

Apparatus according to claim 11, wherein the control circuit is adapted to generate the output signal, responsive to the synchronization of the field frequencies with the driving frequency, so as to indicate a phase of the current flowing in the at least one sensor coil, relative to a phase of the electromagnetic fields.

Claim 15

Apparatus according to claim 11, wherein the control circuit comprises a voltage-to-frequency (V/F) converter, which is coupled to generate the output signal with an output frequency that varies responsive to the electrical current flowing in the at least one sensor coil.

Claim 16

Apparatus according to claim 11, wherein the transponder is adapted to be inserted, together with the object, into a body of a subject, while the one or more field generators and the RF driver are placed outside the body.

Claim 17

Apparatus for tracking an object, comprising: a radio frequency (RF) driver, adapted to radiate a RF driving field toward the object; one or more field generators, adapted to generate electromagnetic fields in a vicinity of the object; a wireless transponder, fixed to the object, the transponder comprising: at least one sensor coil, coupled so that an electrical current flows in the at least one sensor coil responsive to the electromagnetic fields; a control circuit, coupled to the at least one sensor coil so as to generate an output signal indicative of an amplitude of the current and of a phase of the current relative to a phase of the electromagnetic fields; and a power coil, coupled to receive the RF driving field and to convey electrical energy from the driving field to the control circuit, and further coupled to transmit the output signal generated by the control circuit; and a signal receiver, adapted to receive the output signal transmitted by the power coil and, responsive to the amplitude and phase of the current indicated by the output signal, to determine an orientation of the object.

Claim 18

Apparatus according to claim 17, wherein the at least one sensor coil comprises a single sensor coil, and wherein the signal receiver is adapted, responsive to the indicated phase of the current, to determine a direction of the orientation of the transponder.

Claim 19

Apparatus according to claim 17, wherein the control circuit comprises a voltage-to-frequency (V/F) converter, which is coupled to generate the output signal with an output frequency that varies responsive to the electrical current flowing in the at least one sensor coil.

Claim 20

Apparatus according to claim 17, wherein the transponder is adapted to be inserted, together with the object, into a body of a subject, while the one or more field generators and the RF driver are placed outside the body.

Claim 21

Apparatus for tracking an object, comprising: a radio frequency (RF) driver, adapted to radiate a RF driving field toward the object; one or more field generators, adapted to generate electromagnetic fields in a vicinity of the object; a wireless transponder, fixed to the object, the transponder comprising: at least one sensor coil, coupled so that an electrical current flows in the at least one sensor coil responsive to the electromagnetic fields; a voltage-to-frequency (V/F) converter, coupled to the at least one sensor coil so as to generate an output signal with an output frequency that varies responsive to an amplitude of the electrical current flowing in the at least one sensor coil; and a power coil, coupled to receive the RF driving field and to convey electrical energy from the driving field to the control circuit, and further coupled to transmit the output signal generated by the control circuit; and a signal receiver, adapted to receive the output signal transmitted by the power coil and, responsive to the output frequency, to determine coordinates of the object.

Claim 22

Apparatus according to claim 21, wherein the transponder is adapted to be inserted, together with the object, into a body of a subject, while the one or more field generators and the RF driver are placed outside the body.

Claim 23

A wireless position transponder for operation inside a body of a subject, the transponder comprising: at least one sensor coil, coupled so that an electrical current flows in the at least one sensor coil responsive to one or more electromagnetic fields applied to the body in a vicinity of the transponder; a voltage-to-frequency (V/F) converter, coupled to the at least one sensor coil so as to generate an output signal with an output frequency that varies responsive to an amplitude of the electrical current flowing in the at least one sensor coil, such that the output frequency is indicative of coordinates of the transponder inside the body; and a power coil, adapted to receive a radio frequency (RF) driving field applied to the body in the vicinity of the transponder, and coupled to convey electrical energy from the driving field to the control circuit, and further coupled to transmit the output signal generated by the control circuit so that the signal can be received by processing circuitry outside the body for use in determining the coordinates.

Claim 24

A transponder according to claim 23, wherein the sensor coil, V/F converter and power coil are together adapted to be fixed inside an elongate probe, for insertion into the body, so as to enable the processing circuitry to determine the coordinates of a distal end of the probe.

Claim 25

A transponder according to claim 23, wherein the sensor coil, V/F converter and power coil are together adapted to be fixed inside an implant, so as to enable the processing circuitry to determine the coordinates of the implant within the body.

Claim 26

A transponder according to claim 23, wherein the V/F converter is adapted to operate powered solely by the electrical energy conveyed thereto by the power coil.